Automated weighing scale keeps materials moving

A Canadian pharmaceutical manufacturer has made a science out of managing totes and bins by linking a network of calibrating load cells to a database to monitor and optimize weighing operations.

By Paul Thomas, Contributing Editor, A-B Journal

Even before it restarted production in 2004, Apotex, Inc.’s Etobicoke, Ontario, Canada, facility garnered plenty of attention as a showcase for innovative plant design and automation (Pharmaceutical Manufacturing magazine).

The facility, following a $238 million expansion, is a multilevel symphony of automated lifts, conveyors and automatic guided vehicles (AGVs) that move product from storage to production suites to warehouses at the behest of the plant’s execution system. Radio-frequency identification (RFID) tags and barcodes keep track of bins, totes and other assorted containers, and send batch and product weight information to the system.

When he was put in charge of logistics for the new site, project leader Chip Hill knew it was a rare opportunity. “We got the signal from upper management to automate as much as possible, but few details on how,” Hill says. “We had to fill in the blanks.”

A new “Yield Check” system filled one of these blanks. Hill and Dave Patterson, vice president of Grantek Systems Integration Inc., Burlington, Ontario, Canada, the lead systems integrator on the expansion project, linked a network of calibrated load cells to a database to monitor and optimize weighing and provide redundant information regarding in-process totes and bins.

Since containers are made of materials such as stainless steel, and operators rarely enter the processing suite, the Yield Check system — eight automated weighing scales for bins and eight for totes — is really the only way operators have of knowing how much product is in them. If, for example, a bin is partially full, it’s taken by an automatic storage and retrieval system to a scale for weighing, and the control system sends these data to the corporate enterprise resource planning (ERP) system. If it’s empty, it goes straight to the automatic bin washers.

This was a huge advantage for implementation and maintenance, Hill says.

“If we had a load cell or PLC go down in the field, we wanted to make sure a technician could replace it without much effort and not interfere with operations,” he says.

Hardy’s push-button electronic C2 automated weighing scale calibration eliminated the need for cumbersome test weights. Loadcell data are recorded in a database so operators don’t have to calibrate each time from scratch. PLCs can be programmed to calibrate after each shift or batch.

Hardy’s INTEGRATED TECHNICIAN was also a key reason the technology was chosen, says Gene Chae, senior developer at Grantek. This feature allows operators to check scales upon demand — to, for instance, check millivolts, excitation or resistance on each load cell at any given time.

The implementation also required some customization. Hardy’s load cells had to be specially designed to accommodate robots that are anything but delicate and that also vibrate bins to remove product.

“Dropping a 4,500-pound bin at so many feet per second isn’t a gentle process,” says Alan Davis, president of CTH Industrial Weighing Controls, Hardy Instruments’ authorized sales representative. Shock-absorbing load cells were built with rubber, disc-shaped grommets between the cells and mounting plates.

A Real-Time Link to ERP Weigh-scale data are event-driven and gathered by the PLCs, which are linked to the company’s secure virtual private network (VPN) using a system designed by Grantek’s SAP interface team. That data are then transferred to a Rockwell Software RSView database for plant-floor viewing.

Grantek’s SAP Interface team also worked with SAP to provide real-time integration of load cell data with the back end of the Apotex ERP, allowing for constant production monitoring and materials management. Through a human-machine interface (HMI), an operator can push a button and trigger a materials update or initiate batch production. The HMI signals SAP, which calls the warehouses and polls all bins and totes to determine product levels and whereabouts, then sends those data back to the operator. Patterson compares the operator to a chef in a kitchen who, with the touch of a button, can survey cooking utensils and ingredients needed for a particular recipe, and call them all automatically to the kitchen door.

If ingredients are running low, SAP notifies schedulers and purchasers in real time. “You don’t need to wait until the next morning to order, when it might be too late,” Patterson says. Historical tare weight information is gathered in a database and is logged to assist Apotex in 21 CFR Part 11 compliance. Apotex is also beginning to link information from the Etobicoke facility with data from other plants by way of SAP.

The advanced automation at Etobicoke hasn’t replaced operators altogether, but has required them to step up their performance. “They’ve really had to learn to understand what the building is supposed to do,” Hill says. “It’s a big monster, and its parts all work together.” ABJ Allen-Bradley, Encompass, Rockwell Automation, Rockwell Software and RSView are trademarks of Rockwell Automation, Inc.